Heat Transfer Fluids, Systems, Efficiencies and Methods

ABSTRACT

Heat transfer compositions, methods, efficiencies, and systems are disclosed. The compositions have four or more heat transfer components/constituents that have been selected such that the compositions provide an operating performance and energy efficiency that are comparable to, or better than, the performance of R22 and currently available R22 replacements. The four or more constituents have sequenced boiling temperatures that work together to extend the phase change, thereby elongating the heat absorption phase and increasing efficiency. In some embodiments the heat transfer constituents include 15-25% by weight R32, 1-5% by weight R125, 50-70% by weight R134a, and 10-20% by weight R227ea. The compositions may also include 0.5-3.5% by weight R236.

This application claims the benefit of priority to U.S. Provisional Application No. 62/072931 filed on Oct. 30, 2014 and U.S. Provisional Application No. 62/009102 filed on Jun. 6, 2014, and, both of which are incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The field of the invention is heat transfer fluids, systems, efficiencies, and methods.

BACKGROUND

The background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.

Heat transfer fluids (e.g., refrigerants) are commonly used in various heat transfer systems, including air conditioning, refrigeration, freezers, heaters, and the like. Many formulations for heat transfer fluids are known.

At the time this application is filed, R22 (cholordifluoromethane) is being phased out in many developed countries due to its ozone depletion potential (ODP) and high global warming potential (GWP). There is currently a need for new compositions of heat transfer fluids that can serve as a replacement for R22 and that have improved ODP and GWP.

Suitable R22 replacements preferably have similar or better performance metrics (e.g., amperage, pressure differential, operational temperatures, cycle time, etc.) and better ODP and GWP than R22. Replacement compositions also preferably carry mineral oil (e.g., mineral oil is miscible in the heat transfer fluid) so that the replacement fluid can be used with R22 based heat transfer systems that currently use mineral oil as a lubricant. In addition, replacement compositions preferably have low flammability levels that meet industry standards and governmental regulations.

Various heat transfer compositions are described in WO2011/077088, AU2007338824, US20070284078, U.S. Pat. No. 6,511,610, U.S. Pat. No. 6,521,141, and RU2135541. Unfortunately, heat transfer fluids that are currently available suffer from one or more disadvantages when used as a substitute for R22.

All publications identified herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.

Thus, there is still a need for improved heat transfer fluids, systems, efficiencies and methods.

SUMMARY OF THE INVENTION

The inventive subject matter provides apparatus, systems and methods in which a heat transfer fluid composition comprises the following heat transfer components: R32 present in an amount of 15-25% by weight; R125 present in an amount of 1-5% by weight; R134a present in an amount of 50-70% by weight; and R227ea present in an amount of 10-20% by weight. These weight percentages represent the weight of a particular heat transfer component in the composition relative to the total weight of heat transfer components in the composition.

In some embodiments the heat transfer composition optionally includes R236 present in an amount of 0.5-3.5% by weight. In some embodiments, R236 could comprise one or more of R236fa and R236ea.

In another aspect of some embodiments, the heat transfer fluid composition could include, or used in combination with, a lubricant. It is further contemplated that the lubricant composition could be a mineral oil, alkylbenzene oil, and synthetic oil, or any combination thereof.

The heat transfer components and their respective amounts are preferably selected such that the heat transfer compositions have a flammability classification of A1 as defined by ISO817:2009, a Global Warming Potential (GWP) of less than 2000, at Integratation Time Horizon (ITH) of 100 years.

The heat transfer compositions described herein can be used in heat transfer systems comprising: a compressor; a condenser fluidly coupled with the compressor; an expansion device (e.g., fixed orifice, capillary tubes and various expansion valve types) fluidly coupled with the condenser; and an evaporator fluidly coupled with the expansion device. Examples of heat transfer systems include, but are not limited to, air conditioning, refrigeration, freezers, and heaters. The heat transfer system is designed to transfer heat with an external environment by utilizing the gas-to-liquid and liquid-to-gas phase change properties of the heat transfer composition.

Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

DETAILED DESCRIPTION

The following discussion provides many example embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive elements, the inventive subject matter is considered to include all possible combinations of the disclosed elements. Thus if one embodiment comprises elements A, B, and C, and a second embodiment comprises elements B and D, then the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if not explicitly disclosed.

Applicant has unexpectedly discovered that the heat transfer compositions disclosed herein have a measured operating performance and energy efficiency that are comparable to, or better than, the performance of R22 and R22 replacements. The disclosed compositions have been developed to (i) deliver operating performance that is comparable with R22 and (ii) reduce energy consumption compared to R22 through reduced equipment amperage and reduced run-times. As a result of increased energy efficiency, the mechanical and operational load of the heat transfer system is reduced in measurable amounts, where the result can be characterized through reduced energy consumption.

A series of tests were performed on a split unit heat transfer system in a controlled environment and initial test data was acquired in real time using digital data log technologies. Fifteen data points were collected and processed through an internal data accumulation process for standardized data measurement. Measured data was further processed through Industry standard NIST REPROP and Refleak software to measure viability and acceptability of the test results. Testing comparisons provided validation of measured refrigerant performances and the degree of variance to established industry operating models for operating performance, efficiency and acceptability (measured as Delta T, Compressor Amps, and EPA flammability requirements, respectively). The captured data was measured against this industry standard. The test results for four compositions are shown in the table below.

TABLE A Performance Outside Latent Liquid Vapor Air Heat of Phase Phase Heat Transfer Constituents [% WT] Temp Vaporization @ 100 F. @ 100 F. Composition R125 R32 R134a R227 R236 R600a Delta T Amps (F.) (kJ/kg) (psig) (psig) Composition 1 3% 23% 55% 19% 24.9 5.2 79.8 231 199 169 Composition 2 4% 20% 63% 12% 1% 23.8 5.0 79.1 232 194 165 Composition 3 4% 21% 61% 13% 1% 22.8 5.2 88.8 232 194 165 Composition 4 10%  10% 78% 2% 24.7 4.9 77.0 231 175 155

The conclusions derived from these tests provide definable validation of the inventive subject matter as to the creation of unexpected and not seen before patterns of system operating performance based on comparable R22 capacities being attained through lower operating pressures and temperatures while providing shorter operating cycles and lower amperages.

The inclusion of a Hydrocarbon increased the potential of non-compliance in accordance with EPA acceptability guidelines for flammability.

During the testing periods it was noted that many compositions would work towards meeting the performance criteria established for the inventive subject matter but would not meet the evaluative requirements for flammability as established by governing bodies. These compositions remain viable for many applications where R22 is used, such as refrigeration, chillers and residential systems. For the purposes of maximizing the discovered low pressure/low temperature performance of the current inventive subject matter, one of many applications can be in the heating and cooling requirement of small, medium and large sized HVAC systems.

In the development of the inventive subject matter, it was discovered that by utilizing multiple constituents (e.g., multiple heat transfer components), which provide sequenced or spaced ‘boiling points’, a superior heat transfer capability was found to be greater than otherwise expected based on the chemical heat absorption attributes of each constituent individually and collectively. The staggered boiling points create a ‘domino’ effect as each individual constituent reaches its boiling point, maximizes its heat absorption until it starts to saturate just as the next sequential constituent reaches its boiling point, maximizes its heat absorption until it starts to saturate. This process continues for all of the heat transfer components, thus creating a more consistent phase change during the liquid-to-gas and gas-to-liquid phase changes across the evaporator and condenser coils of the equipment. This effect is best illustrated with at least four heat transfer components, and is further illustrated with five or more heat transfer components that have sequenced boiling points. The inventive subject matter provides heat transfer compositions that have at least four heat transfer components that have been purposely selected to provide staggered boiling points and related P/T charts. Five possible heat transfer components and their respective boiling points are provided below:

1. R32: boils at −51.7 C (−61.0 F)

2. R125: boils at −48.0 C (−54.0 F)

3. R134a: boils at −26.6 C (−15.8 F)

4. R227ea: boils at −16.4 C (+2.5 F)

5. R236: boils at −1.0 C (+31.0 F)

The pressure/temperature graph below illustrates the sequenced (e.g., “stacked” or “staggered”) nature of these five heat transfer components.

While R32, R125, R134a, R227ea, and R236fa are shown in the data above, the inventive subject matter includes alternative heat transfer components that have similar characteristics (e.g., flammability, boiling temperature/pressure, GWP, ODP, etc.) to provide a heat transfer composition with comparable performance to R22 and reduced energy consumption compared to R22. For example, the heat transfer composition could included R32 present in an amount of 15-25% by weight, R125 present in an amount of 1-5% by weight, and three additional components that have boiling temperatures within the ranges of −55° C. and −35° C., −40° C. and −20° C., and −25° C. and −5° C., respectively, at 14.696 PSIA. The three additional components are preferably selected such that the heat transfer composition has a latent heat of vaporization of at least 230 kJ/kg and a vapor phase pressure at 100° F. of less than 170 PSIG at 100° F. Those of ordinary skill in the art will also appreciate that new heat transfer components developed after the filing of this application may also be used consistently with the inventive principles described herein to provide a heat transfer composition that accomplishes the stated objectives (e.g., staggered boiling temperatures, improved latent heat of vaporization, lower liquid/vapor phase pressure, acceptable flammability, etc.).

It should also be appreciated that the additional heat transfer components could be selected based on their partial pressures at a given temperature rather than, or in addition to, their boiling temperatures. For example, the first additional component could have a partial pressure between 73 PSIG and 93 PSIG at 0° C., 107 PSIG and 127 PSIG at 10° C., and/or 233 PSIG and 253 PSIG at 35° C. The second additional component could have a partial pressure between 18 PSIG and 38 PSIG at 0° C., 35 PSIG and 55 PSIG at 10° C., and/or 104 PSIG and 124 PSIG at 35° C. The third component could have a partial pressure between 4 PSIG and 24 PSIG at 0° C., 16 PSIG and 36 PSIG at 10° C., and/or 64 PSIG and 84 PSIG at 35° C.

While R32 is a highly effective refrigerant, it has a flammable rating and high operating pressure that increases electricity consumption. The disclosed compositions use multiple flame retarding or flame inhibiting constituents with varying boiling points and operating pressures to offset both the flammability and high operating pressure of R32. The sequence spaced boiling points of the multiple constituents effectively offset the flammability and high operating pressure of R32 to provide a non-flammable, low pressure, energy efficient and highly effective heat transfer composition.

The table below shows test data for composition 5, which is represented by the constituents at weight percentages represented as follows: R-32/125/134a/227ea/236fa (20/4/61/12/3). The test data for composition 5 demonstrates that the inventive subject matter disclosed herein can provide a compressor amp savings of 11% compared to R22 and an energy consumption reduction of 15% compared to R22. (The test data was performed on a Carrier 10 Ton Packaged Rooftop Heat Pump Unit with two compressors).

Outside Return Supply Amp Energy R-22 Air Air Air Delta Savings Run Time Consumption Replacement Temp Temp Temp T Comp. vs. R-22 Differential Reduction vs. Refrigerants (F.) (F.) (F.) (F.) Amps (Inc./Dec.) (Inc./Dec.) R-22 (Inc./Dec.) R424a 87.0 81.9 64.2 17.7 7.0 11% −36% −25% MO99 87.1 82.9 62.7 20.2 7.7  2% −20% −18% R422B 75.7 78.0 62.7 15.3 7.0  8% −41% −33% R407C 85.6 80.4 60.8 19.6 8.1 −2.0%  −23% −25% Composition 5 81.3 74.6 52.5 22.1 6.8 13%  2%  15%

The table below compares the ability of two compositions (composition 6 and composition 7) to absorb heat (defined as the “Latent Heat of Vaporization”) compared to several known R22 replacement heat transfer compositions. The constituents and weight percentages of composition 6 are as follows: R-32/125/134a/227ea (21/4/60/15). The constituents and weight percentages of composition 7 are as follows: R-32/125/134a/227ea/236fa (22/5/59/10/4).

R22 Latent Heat of Replacement Vaporization Liquid Phase Vapor Phase Refrigerants (kJ/kg) @ 100 F. (psig) @ 100 F. (psig) R407C 236 226 196 R407F 244 246 218 R421A 186 197 181 R438A 208 211 187 R442A 244 252 222 Composition 6 231 195 166 Composition 7 234 197 166

As shown by the test data above, composition 6 and composition 7 have a high level of heat absorption at a significantly lower liquid and vapor pressure compared to the R22 replacement compositions. This combination of high heat absorption and lower pressure reduces the energy requirements of the HVAC equipment, creating a reduction in energy consumption. The test data also shows the comparison between a composition with and without the addition of R236. The addition of R236 in even a small weight percentage to volume of product shows a substantial increase in latent heat of vaporization, while achieving measurable lower pressure.

During testing, the Applicant also unexpectedly discovered that the compositions disclosed above began to absorb heat in less time upon system startup and reached optimal performance faster as compared to R22. This attribute known as “ramp time” resulted in a reduction in the equipment ‘on-time or run-time’ as compared to the R22 based equipment which reduces energy consumption.

The data presented below is a representation of ‘ramp time’ observation for the inventive subject manner as it is cycles from off to on in system operation. The slope of the ramp time curve (in red) represents the disclosed composition's ability to absorb heat faster and obtain optimum operating performance quicker as a result of the sequence spaced boiling point capabilities. This decreased time to obtain optimum operating performance results in a shorter cycle time and reduced of kilowatt hours of 33%.

Moreover, the disclosed compositions have demonstrated in testing the characteristic and capability of reducing the temperature of the air flow being provided to the space being serviced (Supply Air) as the evaporator performs at a higher degree of cooling. Testing has demonstrated that the temperature range of the evaporating function is typically better than or equivalent to heat transfer systems using R22 Replacement heat transfer fluids. The test data below for composition 5 illustrate this finding. (The test data was performed on a Carrier 10 Ton Packaged Rooftop Heat Pump Unit with two compressors).

R-22 Outside Return Air Supply Air Replacement Air Temp Temp Temp Delta T Refrigerants (F.) (F.) (F.) (F.) R424a 87.0 81.9 64.2 17.7 MO99 87.1 82.9 62.7 20.2 R422B 75.7 78.0 62.7 15.3 R407C 85.6 80.4 60.8 19.6 Composition 5 81.3 74.6 52.5 22.1

In an additional demonstration of reduced operating temperatures as a result of the capability of the novel compositions provided herein, the operational temperature of the compressor of the heat transfer system has demonstrated a reduced physical temperature (e.g., compressor operates at a lower temperature).

Another key feature of the compositions disclosed herein is their ability to carry mineral oil. In particular, some of the heat transfer components in the composition are selected specifically selected for their ‘oil carrying’ characteristics. It is known that there are conflicts between some compressor oils (e.g., mineral, POE, PAG) and today's refrigerants that requires the replacement of the compressor oils or by adding a highly flammable hydrocarbon to the refrigerant. The attributes of the compositions disclosed herein specifically address this compressor oil issue by utilizing the specific oil carrying characteristics of selected constituents to achieve lubrication in the HVAC system without the need to replace the compressor oil or the need to add flammable hydrocarbons to the refrigerant, allowing for continued system operation without any requirement of oil replacement or augmentation.

In one aspect of some embodiments, the inventive subject matter includes a heat transfer composition that adequately carries mineral oil in R22 based equipment to obtain lubrication without using a hydrocarbon component in the heat transfer composition. The disclosed compositions include R227ea and R236 in sufficient amounts to adequately carry mineral oil to achieve lubrication in the R22 based equipment while still maintaining a flammability classification of A1. In some embodiments the composition includes up to 15-25% by wt of R32; 10-20% by wt of R227ea, and 0.5-3.5% by wt. of R236. The composition may additionally include 50-70% by wt of R134a, and 1-5% by wt of R125.

One of the key findings of the inventive subject matter has been to recognize that R236 has one of the strongest dipole moment of all HFC based refrigerants. (i.e., bond polarity is measured by its dipole moment). The strong dipole moment gives R236 the ability to induce hydrogen bonding with proton acceptor compounds.

The inventive findings have provided a theory that the hydrogen bonding attributes of R236 could be bonding with the remainder of the composition, thus extending the phase change of the other constituents and thereby elongating the heat absorption phase and increasing the efficiency of the equipment.

Additionally, because of the high boiling point of R236, tiny droplets likely remain in a liquid phase suspended in the vapor of the other constituents, which could act as a catalyst helping to compress the vapor back into a liquid reducing the work of the compressor.

It is believed that these droplets utilize chemical, polar energy to help induce the gas to liquid phase change thus lowering the kinetic energy and electricity consumption required by the compressor. As such, the inventive subject matter includes compositions that have five or more heat transfer components with sequenced boiling temperatures, wherein the fifth (or last) component has a high polarity, wherein the polarity of the molecule is the sum of all of the bond polarities in the molecule. In some embodiments, the polarity of the fifth (or last) constituent is preferably near, or even higher than, the polarity of R236-6.7±0.5 10-24cm3. In yet other embodiments, the fifth (or last) component could not only have the highest boiling temperature of all the heat transfer components in the composition, but could also have the highest polarity of all the heat transfer components in the composition.

The features, functions and capabilities of the compositions disclosed herein may be further enhanced by the incorporation of a lubricant, which can be added in pre/post production processes to further enhance the capacity, energy savings and temperature reductions typically experienced when using the disclosed compositions.

One should appreciate that the disclosed techniques provide many advantageous technical effects including heat transfer fluids for heat transfer systems that provide improved performance metrics.

In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

Unless the context dictates the contrary, all ranges set forth herein should be interpreted as being inclusive of their endpoints and open-ended ranges should be interpreted to include only commercially practical values. Similarly, all lists of values should be considered as inclusive of intermediate values unless the context indicates the contrary.

As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.

The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.

Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.

As used herein, and unless the context dictates otherwise, the term “coupled to” is intended to include both direct coupling (in which two elements that are coupled to each other contact each other) and indirect coupling (in which at least one additional element is located between the two elements). Therefore, the terms “coupled to” and “coupled with” are used synonymously.

It should be apparent to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refers to at least one of something selected from the group consisting of A, B, C . . . and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc. 

What is claimed is:
 1. A heat transfer composition comprising heat transfer components present in the following percentages: R32 present in an amount of 15-25% by weight; R125 present in an amount of 1-5% by weight; R134a present in an amount of 50-70% by weight; and R227ea present in an amount of 10-20% by weight.
 2. The heat transfer composition of claim 1, further comprising R236 present in an amount of 0.5-3.5% by weight.
 3. The heat transfer composition of claim 1, wherein the R32, R125, R134a and R227ea collectively comprise at least 96.5% of the heat transfer composition.
 4. The heat transfer composition of claim 1 further comprising a lubricant composition.
 5. The heat transfer composition of claim 4, wherein the lubricant is a combination of one or more of a mineral oil, alkylbenzene oil, and synthetic oil.
 6. The heat transfer composition of claim 1, wherein the amounts are selected such that the composition has a flammability classification of Al as defined by ISO817:2009.
 7. The heat transfer composition of claim 1, wherein the amounts are selected such that the composition has a Global Warming Potential (GWP) of less than 2000 at Integration Time Horizon (ITH) of 100 years.
 8. A heat transfer system comprising: a compressor; a condenser fluidly coupled with the compressor; an expansion device fluidly coupled with the condenser; an evaporator fluidly coupled with the expansion device; and the heat transfer composition of claim
 1. 9. A heat transfer composition that adequately carries mineral oil in an R22-based heat transfer system without hydrocarbon utilizing R227ea and R236, the heat composition fluid comprises: between 15-25 wt % of R32; between 10-20 wt % of R227ea; and between 0.5-3.5 wt % of R236.
 10. The heat transfer composition of claim 9, further comprising 1-5 wt % of R125.
 11. The heat transfer composition of claim 9, further comprising 50-70 wt % of R134a.
 12. The heat transfer composition of claim 9, further comprising at least one of R125 and R134a.
 13. The heat transfer composition of claim 9, further comprising R125 and R134a.
 14. A heat transfer composition for an R22 based heat transfer system, the composition comprising: R32 present in an amount of 15-25% by weight; R125 present in an amount of 1-5% by weight; and wherein the composition has a latent heat of vaporization of at least 230 kJ/kg and a vapor phase pressure at 100° F. of less than 170 PSIG at 100° F.
 15. The heat transfer composition of claim 14, wherein the heat transfer fluid further comprises 50-70 wt % of R134a.
 16. The heat transfer composition of claim 15, wherein the heat transfer fluid further comprises 10-20 wt % of R227ea.
 17. The heat transfer composition of claim 16, wherein the heat transfer fluid further comprises 0.5-3.5 wt % of R236.
 18. The heat transfer composition of claim 14, wherein the heat transfer fluid further comprises at least two of R134a, R227ea, and R236.
 19. The heat transfer composition of claim 15, wherein the heat transfer fluid further comprises R134a, R227ea, and R236.
 20. A heat transfer composition for a heat transfer system, comprising R32 and at least second, third, and fourth additional constituents, wherein: a) the second additional constituent boils at between −55° C. and −35° C. at 14.696 PSIA; b) the third additional constituent boils at between −40° C. and −20° C. at 14.696 PSIA; and c) the fourth additional constituent boils at between −25° C. and −5° C. at 14.696 PSIA.
 21. The heat transfer composition of claim 20, wherein at least one of the second, third, and fourth additional constituents is selected from the group consisting of R125, R134a, R227ea, and R236.
 22. The heat transfer composition of claim 20, wherein at least two of the second, third, and fourth additional constituents are selected from the group consisting of R125, R134a, R227ea, and R236.
 23. The heat transfer composition of claim 20, wherein the second, third, and fourth additional constituents are each selected from the group consisting of R125, R134a, R227ea, and R236.
 24. The heat transfer composition of claim 20, wherein the second, third, and fourth additional constituents are R125, R134a and R227ea, respectively.
 25. The heat transfer composition of claim 23, further comprising a fifth additional constituent that boils at between −10° C. and 10° C. at 14.696 PSIA. (R236).
 26. The heat transfer composition of claim 25, wherein: a) the second additional constituent comprises R125 present in an amount of 1-5% by weight; b) the third additional constituent comprises R134a present in an amount of 50-70% by weight; c) the fourth additional constituent comprises R227ea present in an amount of 10-20% by weight; and d) the fifth additional constituent comprises R236fa present in an amount of 0.5-3.5% by weight.
 27. The heat transfer composition of claim 25, wherein the fifth constituent has a high bond polarity.
 28. The heat transfer composition of claim 25, wherein the fifth constituent has a stronger dipole moment than each of R32, the second constituent, the third constituent, and the fourth constituent.
 29. A heat transfer composition for a heat transfer system, comprising R32 and at least second, third, and fourth additional constituents, wherein at a temperature of 0° C.: a) the second additional constituent has a partial pressure of between 73 PSIG and 93 PSIG; b) the third additional constituent has a partial pressure of between 18 PSIG and 38 PSIG; and c) the fourth additional constituent has a partial pressure of between 4 PSIG and 24 PSIG.
 30. The heat transfer composition of claim 29, wherein at a temperature of 10° C.: a) the second additional constituent has a partial pressure of between 107 PSIG and 127 PSIG; b) the third additional constituent has a partial pressure of between 35 PSIG and 55 PSIG; and c) the fourth additional constituent has a partial pressure of between 16 PSIG and 36 PSIG.
 31. The heat transfer composition of claim 31, wherein at a temperature of 35° C.: a) the second additional constituent has a partial pressure of between 233 PSIG and 253 PSIG; b) the third additional constituent has a partial pressure of between 104 PSIG and 124 PSIG; and c) the fourth additional constituent has a partial pressure of between 64 PSIG and 84 PSIG.
 32. The heat transfer composition of claim 31, further comprising a fifth additional constituent that has a partial pressure of between 0 PSIG and 4 PSIG at 0° C., 6 PSIG and 10 PSIG at 10° C., and 30 PSIG and 50 PSIG at 35° C.
 33. The heat transfer composition of claim 29, further comprising less than 5% by weight of R125a.
 34. The heat transfer composition of claim 29, further comprising less than 70% by weight of R134a.
 35. The heat transfer composition of claim 29, further comprising less than 20% by weight of R227ea.
 36. The heat transfer composition of claim 29, further comprising less than 3.5% by weight of a component other than R134a, R125, R227ea, and R236.
 37. A heat transfer composition for a heat transfer system, comprising: R32 present in an amount of 15-25% by weight; a plurality of additional constituents comprising at least second, third, and fourth additional constituents that have sequential boiling temperatures at 14.696 PSIA; and a constituent present in an amount of less than 5% and having a higher boiling temperature than the second, third, and fourth additional at 14.696 PSIA, wherein the constituent is selected to extend the liquid-to-gas phase change time of the composition.
 38. The heat transfer composition of claim 37, wherein the constituent is R236. 